US President Barack Obama says the US has concluded that the Syrian government carried out a chemical weapons attacks near Damascus.
He said the use of chemical weapons affected US national interests and that sending a "shot across the bows" could have a positive impact on Syria's war.
But in the interview with PBS, he said he had not yet made a decision about whether to intervene militarily.
His comments follow a day of behind-the-scenes wrangling at the UN.
The UK had been pushing for permanent members of the UN Security Council to adopt a resolution which would have authorised measures to protect civilians in Syria.
But Syrian ally Russia refused to agree to the resolution and the meeting produced no end to the diplomatic stalemate which has long
